An integrating sphere is a hollow sphere whose shell has different numbers of input ports and output ports and whose interior wall is coated with a reflective and diffusing coating. When luminous flux of a light-emitting diode under test enters the integrating sphere through the input ports, the luminous flux is diffused and reflected multiple times by the interior wall of the integrating sphere, and the amount of luminous flux absorbed by the interior wall during the measurement is determined by the material of the coating on the interior wall, and then the rest of the luminous flux is emitted from the output ports. The integrating sphere is used to collect luminous flux in all directions and detect the optical power, the spatial distribution, and the luminous flux from the output ports due to special designs, and then related parameters of the light-emitting diode are obtained after computation.
The industry currently measures the parameters such as optical power of a light-emitting diode by a conventional commercial instrument system, which comprises an integrating sphere having a diameter of at least 10 inches. With reference to FIG. 2, the integrating sphere comprises a sample holder 2 mounted directly against one of the output ports (not shown) of the integrating sphere, but such design renders the sample holder 2 only suitable for measuring a packaged light-emitting diode. The pins 62 of a packaged light-emitting diode 61 under test are directly inserted into a sample holder body 60 whose bottom is connected to a power supply (not shown), and the power supply provides current or voltage to force the luminous flux emitted by the packaged light-emitting diode 61 to enter the integrating sphere.